In isolated systems, such as flyback converters, the input circuitry (e.g., a primary controller) and the output circuitry (e.g., a secondary controller) are not electrically/galvanically connected to each other. Flyback converters are commonly used as isolated battery chargers and/or front-end AC-DC and DC-DC converters in switch mode power supply applications. For example, a common flyback converter is a buck-boost converter including an inductor that is split to form a transformer. A primary winding of the transformer is coupled to the input circuitry, and a secondary winding of the transformer is coupled to the output circuitry, thus providing the desired isolation between the input circuitry and the output circuitry.
Flyback converters are often preferred for power conversion at low powers, particularly when input voltage variation and output load variations are wide. Their low component count and complexity may be beneficial in incorporating flyback converters into external power adapters used for electronic devices such as cell phones, notebook computers and other consumer electronics equipment.